xref: /qemu/trace/control.c (revision 138ca49a) 
1 /*
2  * Interface for configuring and controlling the state of tracing events.
3  *
4  * Copyright (C) 2011-2016 Lluís Vilanova <vilanova@ac.upc.edu>
5  *
6  * This work is licensed under the terms of the GNU GPL, version 2 or later.
7  * See the COPYING file in the top-level directory.
8  */
9 
10 #include "qemu/osdep.h"
11 #include "trace/control.h"
12 #include "qemu/help_option.h"
13 #include "qemu/option.h"
14 #ifdef CONFIG_TRACE_SIMPLE
15 #include "trace/simple.h"
16 #endif
17 #ifdef CONFIG_TRACE_FTRACE
18 #include "trace/ftrace.h"
19 #endif
20 #ifdef CONFIG_TRACE_LOG
21 #include "qemu/log.h"
22 #endif
23 #ifdef CONFIG_TRACE_SYSLOG
24 #include <syslog.h>
25 #endif
26 #include "qapi/error.h"
27 #include "qemu/error-report.h"
28 #include "qemu/config-file.h"
29 #include "monitor/monitor.h"
30 #include "trace/trace-root.h"
31 
32 int trace_events_enabled_count;
33 
34 typedef struct TraceEventGroup {
35     TraceEvent **events;
36 } TraceEventGroup;
37 
38 static TraceEventGroup *event_groups;
39 static size_t nevent_groups;
40 static uint32_t next_id;
41 static uint32_t next_vcpu_id;
42 static bool init_trace_on_startup;
43 
44 QemuOptsList qemu_trace_opts = {
45     .name = "trace",
46     .implied_opt_name = "enable",
47     .head = QTAILQ_HEAD_INITIALIZER(qemu_trace_opts.head),
48     .desc = {
49         {
50             .name = "enable",
51             .type = QEMU_OPT_STRING,
52         },
53         {
54             .name = "events",
55             .type = QEMU_OPT_STRING,
56         },{
57             .name = "file",
58             .type = QEMU_OPT_STRING,
59         },
60         { /* end of list */ }
61     },
62 };
63 
64 
65 void trace_event_register_group(TraceEvent **events)
66 {
67     size_t i;
68     for (i = 0; events[i] != NULL; i++) {
69         events[i]->id = next_id++;
70         if (events[i]->vcpu_id == TRACE_VCPU_EVENT_NONE) {
71             continue;
72         }
73 
74         if (likely(next_vcpu_id < CPU_TRACE_DSTATE_MAX_EVENTS)) {
75             events[i]->vcpu_id = next_vcpu_id++;
76         } else {
77             warn_report("too many vcpu trace events; dropping '%s'",
78                         events[i]->name);
79         }
80     }
81     event_groups = g_renew(TraceEventGroup, event_groups, nevent_groups + 1);
82     event_groups[nevent_groups].events = events;
83     nevent_groups++;
84 }
85 
86 
87 TraceEvent *trace_event_name(const char *name)
88 {
89     assert(name != NULL);
90 
91     TraceEventIter iter;
92     TraceEvent *ev;
93     trace_event_iter_init(&iter, NULL);
94     while ((ev = trace_event_iter_next(&iter)) != NULL) {
95         if (strcmp(trace_event_get_name(ev), name) == 0) {
96             return ev;
97         }
98     }
99     return NULL;
100 }
101 
102 void trace_event_iter_init(TraceEventIter *iter, const char *pattern)
103 {
104     iter->event = 0;
105     iter->group = 0;
106     iter->pattern = pattern;
107 }
108 
109 TraceEvent *trace_event_iter_next(TraceEventIter *iter)
110 {
111     while (iter->group < nevent_groups &&
112            event_groups[iter->group].events[iter->event] != NULL) {
113         TraceEvent *ev = event_groups[iter->group].events[iter->event];
114         iter->event++;
115         if (event_groups[iter->group].events[iter->event] == NULL) {
116             iter->event = 0;
117             iter->group++;
118         }
119         if (!iter->pattern ||
120             g_pattern_match_simple(iter->pattern, trace_event_get_name(ev))) {
121             return ev;
122         }
123     }
124 
125     return NULL;
126 }
127 
128 void trace_list_events(FILE *f)
129 {
130     TraceEventIter iter;
131     TraceEvent *ev;
132     trace_event_iter_init(&iter, NULL);
133     while ((ev = trace_event_iter_next(&iter)) != NULL) {
134         fprintf(f, "%s\n", trace_event_get_name(ev));
135     }
136 #ifdef CONFIG_TRACE_DTRACE
137     fprintf(f, "This list of names of trace points may be incomplete "
138                "when using the DTrace/SystemTap backends.\n"
139                "Run 'qemu-trace-stap list %s' to print the full list.\n",
140             error_get_progname());
141 #endif
142 }
143 
144 static void do_trace_enable_events(const char *line_buf)
145 {
146     const bool enable = ('-' != line_buf[0]);
147     const char *line_ptr = enable ? line_buf : line_buf + 1;
148     TraceEventIter iter;
149     TraceEvent *ev;
150     bool is_pattern = trace_event_is_pattern(line_ptr);
151 
152     trace_event_iter_init(&iter, line_ptr);
153     while ((ev = trace_event_iter_next(&iter)) != NULL) {
154         if (!trace_event_get_state_static(ev)) {
155             if (!is_pattern) {
156                 warn_report("trace event '%s' is not traceable",
157                             line_ptr);
158                 return;
159             }
160             continue;
161         }
162 
163         /* start tracing */
164         trace_event_set_state_dynamic(ev, enable);
165         if (!is_pattern) {
166             return;
167         }
168     }
169 
170     if (!is_pattern) {
171         warn_report("trace event '%s' does not exist",
172                     line_ptr);
173     }
174 }
175 
176 void trace_enable_events(const char *line_buf)
177 {
178     if (is_help_option(line_buf)) {
179         trace_list_events(stdout);
180         if (monitor_cur() == NULL) {
181             exit(0);
182         }
183     } else {
184         do_trace_enable_events(line_buf);
185     }
186 }
187 
188 static void trace_init_events(const char *fname)
189 {
190     Location loc;
191     FILE *fp;
192     char line_buf[1024];
193     size_t line_idx = 0;
194 
195     if (fname == NULL) {
196         return;
197     }
198 
199     loc_push_none(&loc);
200     loc_set_file(fname, 0);
201     fp = fopen(fname, "r");
202     if (!fp) {
203         error_report("%s", strerror(errno));
204         exit(1);
205     }
206     while (fgets(line_buf, sizeof(line_buf), fp)) {
207         loc_set_file(fname, ++line_idx);
208         size_t len = strlen(line_buf);
209         if (len > 1) {              /* skip empty lines */
210             line_buf[len - 1] = '\0';
211             if ('#' == line_buf[0]) { /* skip commented lines */
212                 continue;
213             }
214             trace_enable_events(line_buf);
215         }
216     }
217     if (fclose(fp) != 0) {
218         loc_set_file(fname, 0);
219         error_report("%s", strerror(errno));
220         exit(1);
221     }
222     loc_pop(&loc);
223 }
224 
225 void trace_init_file(void)
226 {
227     QemuOpts *opts = qemu_find_opts_singleton("trace");
228     const char *file = qemu_opt_get(opts, "file");
229 #ifdef CONFIG_TRACE_SIMPLE
230     st_set_trace_file(file);
231     if (init_trace_on_startup) {
232         st_set_trace_file_enabled(true);
233     }
234 #elif defined CONFIG_TRACE_LOG
235     /*
236      * If both the simple and the log backends are enabled, "--trace file"
237      * only applies to the simple backend; use "-D" for the log
238      * backend. However we should only override -D if we actually have
239      * something to override it with.
240      */
241     if (file) {
242         qemu_set_log_filename(file, &error_fatal);
243     }
244 #else
245     if (file) {
246         fprintf(stderr, "error: --trace file=...: "
247                 "option not supported by the selected tracing backends\n");
248         exit(1);
249     }
250 #endif
251 }
252 
253 void trace_fini_vcpu(CPUState *vcpu)
254 {
255     TraceEventIter iter;
256     TraceEvent *ev;
257 
258     trace_guest_cpu_exit(vcpu);
259 
260     trace_event_iter_init(&iter, NULL);
261     while ((ev = trace_event_iter_next(&iter)) != NULL) {
262         if (trace_event_is_vcpu(ev) &&
263             trace_event_get_state_static(ev) &&
264             trace_event_get_vcpu_state_dynamic(vcpu, ev)) {
265             /* must disable to affect the global counter */
266             trace_event_set_vcpu_state_dynamic(vcpu, ev, false);
267         }
268     }
269 }
270 
271 bool trace_init_backends(void)
272 {
273 #ifdef CONFIG_TRACE_SIMPLE
274     if (!st_init()) {
275         fprintf(stderr, "failed to initialize simple tracing backend.\n");
276         return false;
277     }
278 #endif
279 
280 #ifdef CONFIG_TRACE_FTRACE
281     if (!ftrace_init()) {
282         fprintf(stderr, "failed to initialize ftrace backend.\n");
283         return false;
284     }
285 #endif
286 
287 #ifdef CONFIG_TRACE_SYSLOG
288     openlog(NULL, LOG_PID, LOG_DAEMON);
289 #endif
290 
291     return true;
292 }
293 
294 void trace_opt_parse(const char *optarg)
295 {
296     QemuOpts *opts = qemu_opts_parse_noisily(qemu_find_opts("trace"),
297                                              optarg, true);
298     if (!opts) {
299         exit(1);
300     }
301     if (qemu_opt_get(opts, "enable")) {
302         trace_enable_events(qemu_opt_get(opts, "enable"));
303     }
304     trace_init_events(qemu_opt_get(opts, "events"));
305     init_trace_on_startup = true;
306     qemu_opts_del(opts);
307 }
308 
309 uint32_t trace_get_vcpu_event_count(void)
310 {
311     return next_vcpu_id;
312 }
313